MADEEPOEA. 141 



144. Madrepora diversa. (Plate XVI. fig. B.) 

 Madrepora diversa, Brook, Ann. Mag. N. H. 1891, vol. viii. p. 461. 



Corallum cespitose from a broad incrusting base, 10 cm. high and 18 cm. broad. 

 Branches 4-5 cm. long, 1-3 to 1-8 cm. thick, simple or divided into 2 to 5 little-spreading 

 digitiform branchlets about 2-5 cm. long and 1 cm. thick, obtuse at the apex. Axial coral- 

 lites 3"5 to 4 mm. broad, scarcely exsert. Radial corallites chiefly tubular, with a more or 

 less oblique aperture, very unequal in length and diameter ; all are ascending. The larger 

 ones are 3 to 6 mm. long and 2 to 25 mm. diameter, slightly compressed ; wall thick, but 

 only slightly rounded at the margin; smaller nariform or subimmcrsed corallites occur 

 between the others quite to the apex ; a few are proliferous and 5 to 8 mm. long. About 

 2 cm. from the apex the prominent corallites are nariform or tubo- nariform, with a thick and 

 strongly curved outer wall ; at the base nearly all are immersed. Star indistinct, often only 

 the directive septa are recognizable. Corallum moderately porous ; surface strongly echinu- 

 late ; wall finely striato-echinulate. 



Indo-Pacific Ocean : Diego Garcia, Torres Straits. 



a. Diego Garcia. G. C. Bourne, Esq. [P.]. 91. 4. 9. 4. (Type.) 



b. Thursday Island. Saville-Kent Coll. 92. 6. 8. 309. 



** Branches provided with numerous short proliferous corallites or twigs, 



145. Madrepora spectaMlis. (Plate XVIII. fig. B.) 



Madrepora spectahilis. Brook, Ann. Mag. Nat. Hist. 1892, vol. x. p. 462. 



Corallum corymbose, 28'5 cm. diameter, base 14"5 cm., outer branches oblique and pro- 

 liferous, fusions rare, the upper surface only slightly convex. On the under surface of the 

 outer branches the subdivisions are horizontal, frequently acervate, 1 to 2'7 cm. long, and 

 bear numerous irregular and spreading tubular corallites, 5 mm. or more in length and about 

 2"4 mm. diameter, others are nariform or subimmcrsed. Main branches 6 cm. long and 

 erect near the centre of the corallum, but near the margin the length is 8 or 9 cm. and the 

 branches are arched, with the subdivisions chiefly on the outer side ; the diameter at the base 

 is usually 2 cm. and 1"5 cm. at a point about 1 cm. below the apex ; the central branches are 

 simple, blunt, digitiform, or may be divided near the base into two or three branchlets, the 

 basal parts are usually angular in section owing probably to crowding ; the apices are about 

 25 cm. apart; the greatest diameter (including corallites) is often 2*5 cm. in the middle of 

 a branch. Axial corallites very stout, hemispherical, 6 to 7 or even 8 mm. diameter, aperture 

 1-5 mm. The radial corallites vary considerably in form and regularity in diflerent parts of 

 the corallum ; on the marginal branchlets nearly all are tubular or subtubular, with the inner 

 part of the wall more or less incomplete, and extend at an angle of about 45°; length 

 2 to 2*5 mm., diameter 1*5 to 1'75 mm. ; wall a little thickened excepting in the inner part, 



u 



